Radar case study on aesa radar

Active Electronically Scanned Arrays are considered a phased array system, which consists of an array of antennas which form a beam of radio waves that can be aimed in different directions without physically moving the antennae themselves. The primary use of AESA technology is in radar systems.

1. CASE STUDY REPORT ON
AESA RADAR FOR FIGHTER JETS
PREPARED BY
BAIT VISHAL RAMBHAU
INDULKAR SUYOG
MOHITE SURAJ RAJKUMAR
MOKASHI ONKAR ANIL

UNDER THE GUIDANCE OF
PROF. S.C MUNGHATE


FOR THE FULFILMENT OF THEAWARD DEGREE OF
BACHELOR OF ENGINEERING


DEPARTMENT OF ELECTRONICS AND TELECOMMUNICATION ENGINEERING
GHARDA INSTITUTE OF TECHNOLOGY



APRIL 2019

2. I. INTRODUCTION
A. What is AESA?
Active Electronically Scanned Arrays are considered a phased array system, which consists
of an array of antennas which form a beam of radio waves that can be aimed in different
directions without physically moving the antennae themselves. The primary use of AESA
technology is in radar systems.
The evolution of ASEA technology can be traced back to the early 1960s with the
development of the passive electronically scanned array (PESA) radar, a solid state system
which takes a signal from a single source and uses the phase shifter modules to selectively
delay certain parts of the signal while allowing others to transmit without delay.
Transmitting the signal in this way can produce differently shaped signals, effectively
pointing the signal beam in different directions. This is sometimes referred to as beam
steering.
The first AESA systems were developed in the 1980s and had many advantages over the
older PESA systems. Unlike a PESA, which uses one transmitter/receiver module, AESA
uses many transmitter/receiver modules which are interfaced with the antenna elements and
can produce multiple, simultaneous radar beams at different frequencies.
AESA systems are currently used on many different military platforms, including military
aircraft and drones, to provide superior situational awareness.


Figure 1: Basic Concept of AESA RADAR

3. Figure 2: RBE2 AESA RADAR
II. LIMITATION OF PESA RADAR AND SCOPE FOR AESA RADAR
In PESA, there is a single high-power transmitter source, often an older device like
a Klystron or a Traveling-wave tube. These devices can amplify RF signals at microwave
frequencies up to very high powers and then there is a single antenna horn radiating the
signal out. After the signal is radiated there is an RF “lens”. An RF “lens” is an array of
thousands elements that can selectively delay a portion of the RF signal. So by delaying the
radiated RF signal in a particular shape, beam shapes can be formed that allow the beam to
be steered or spoiled to serve specific purposes.
In AESA, the thousands of phase-shifting elements are also themselves transmitters and
antennas. The IF signal from the REX is fed to each of the AESA elements, along with a
digital “command” which tells the element how to delay the signal to form a particular
beam. The individual element does the RF up-conversion and power amplification, along
with phase shifting in order to form and steer a beam. Each radiating module is much less
powerful than the Klystron or the TWT, but the sum of all of the AESA elements allows for
high total power levels.
With PESA, you require a precision set of waveguides in order to get the high power signal
from the common amplification source to all of the phase shifters. This ultimately makes the
radar larger, it has special space constraints, it is heavier, and it is more difficult to
manufacture. AESA radars only require a flat panel with all of the elements installed. Think
of it as a frame with a bunch of circuit cards plugged in. The panel can be separated from the
REX and connected only with cables allowing it to be more easily integrated onto different
platforms.
AESA also allows the use of solid state devices for RF generation and amplification. Single
solid-state devices were never capable of generating the power needed at a single source for
a PESA radar. But when split up over thousands of elements, now you can use solid-state,
and you end up getting much better radar efficiency, and can take advantage of modern
solid-state advances in silicon technology.

4. III. ADVANTAGES OF AESA OVER PESA

1. Resistance to Electronic Jamming
One of the major advantages of an AESA system its high degree of resistance to electronic
jamming techniques. Radar jamming is usually done by determining the frequency at which
an enemy radar is broadcasting and then transmitting a signal at that same frequency to
confuse it. Over time, engineers developed a way to counteract this form of jamming by
designing radar systems which could change their frequency with each pulse. But as radar
advanced, so did jamming techniques. In addition to changing frequencies, AESA systems
can distribute frequencies across a wide band, even within individual pulses, a radar
technique called “chirping”. This combination of traits makes it much harder to jam an
AESA system than other forms of radar.

2. Low Interception
AESA systems also have a low probability of intercept by an enemy radar warning receiver
(RWR). An RWR allows an aircraft or vehicle to determine when a radar beam from an
outside source has struck it. In doing so, it can also determine the beam’s point of origin, and
thus, the enemy’s position. AESA systems are highly effective in overcoming RWRs.
Because the “chirps” mentioned above change frequency so rapidly, and in a totally random
sequence, it becomes very difficult for an RWR to tell whether the AESA radar beam is, in
fact, a radar signal at all, or just part of the ambient “white noise” radio signals found all
over the world.
3. Increased Reliability
Yet another benefit of using AESA systems is that each module operates independently, so a
failure in a single module will not have any significant effect on overall system performance.
AESA technology can also be used to create high-bandwidth data links between aircraft and
other equipped systems.

4. Multi-Mode Capability
This radar technology also supports multiple modes that allow the system to take on a wide
variety of tasks including:
 Real beam mapping
 Synthetic Aperture Radar (SAR) mapping
 Sea surface search
 Ground moving target indication and tracking
 Air-to-air search and track

5. IV. THE FUTURE APPLICATION OF AESA RADAR
As breifly mentioned, as AESA technology has advanced, it has become smaller and more
affordable. This has allowed many countries to incorporate AESA into legacy systems on the
ground, in the sea, and in the air.
In 2016, Raytheon made headlines in the defense tech world by debuting its gallium nitrate
(GaN)-based AESA upgrade to the Patriot Air and Missile Defense System at the
Association of the US Army’s winter trade show. Since its debut, the system has
successfully completed 1000 operating hours. By pairing two of these upgraded systems
facing in opposite directions, they can cover a complete, 360-degree range.
Countries around the world are adding AESA radar into their military aircraft and vessels,
and contractors around the world are rushing to meet the demand. India recently contracted
an Israeli firm to furnish its fleet of Jaguar fighter jets with new AESA radar systems. While
these jets are old, incorporating AESA radar capabilities will allow these and other legacy
craft to remain relevant in a world where electronic warfare is becoming ever more important.
Simply put: without AESA, modern conventional militaries are obsolete. It’s no longer
optional, and it’s going to become more widespread as time goes on.

V. REFERENCES
[1] C. A. Balanis, “Antenna theory,” John Wiley & Sons, INC.
[2] www.rfwirelessworld.com
[3] https://wikipedia.org